A Mexican immigrant in the United States was so elated over his wife's recovery from cancer that he offered to clean the large crucifix outside the New York state church where he spent many hours praying for her to beat the disease.

He was scrubbing grime off the 270-kilogram marble cross when it toppled onto him, crushing his right leg, which had to be amputated.

David Jimenez, 43, is now suing the Roman Catholic church, and his US$3 million (NZ$3.6m) lawsuit is scheduled to go to trial next year.

"He attributed her recovery to his devotion to the cross and Christ hearing his prayers," said Jimenez's lawyer, Kevin Kitson.

Kitson said he filed the lawsuit in March 2011 after the church denied it was liable for the 2010 accident that resulted in six-figure medical bills for Jimenez. The bills were paid by charitable foundations, Kitson said.

The attorney described the Jimenez family as devout Catholics who immigrated to the United States nearly 20 years ago.

During his delivery jobs, Jimenez would pull into the parking lot at St Patrick's Church in the city of Newburgh to pray before the outdoor crucifix for his wife, who was diagnosed with ovarian cancer in 2008.

After she was declared cancer-free, a grateful Jimenez offered to clean the crucifix. While holding onto the cross beam for balance while scrubbing Jesus' face, the crucifix snapped off at its base, sending Jimenez crashing to the ground, Kitson said. The bulk of it landed on Jimenez's right leg, crushing it.

Kitson said a single screw was holding the heavy crucifix to its base.

"There was no anchoring system, just that one screw," he said.

The church raised more than US$7000 (NZ$8500) for Jimenez and his family, but Kitson said his client has been unable to work since the accident.

Frank Raia, a lawyer representing the church, wouldn't discuss the case. The church is part of the Archdiocese of New York, which isn't named as a defendant, Raia said.

"Although the archdiocese and St. Patrick's Church recognise and understand this was a terrible accident and they have empathy for Mr Jimenez and his family, it's our position that the diocese and St Patrick's Church are not liable for the accident."